Fluorescence flow cytometry (FFC) is a fundamental technique in cellular and molecular analysis, yet conventional instruments rely on bulky free-space optics and expert-driven workflows for channel calibration and compensation. We introduce a compact and calibration-free, metasurface-on-chip FC (MOCFC) that replaces filter assemblies or spectrometers with an inverse-designed metasurface array that encodes fluorescence spectra into spatially multiplexed intensity barcodes. We demonstrate statistical profiling of immunolabeled cell populations based on regressed per-fluorophore quantity and extend the approach to multi-cytokine quantification by using a commercial Cytometric Bead Assay (CBA), without the need for channel calibration. By encoding spectral information by a compact on-chip optical metasurface front end and decoding it with end-to-end spectral regression, this metasurface architecture enables quantitative, multi-fluorophore FC in a compact format, opening a promising path toward portable, point-of-care cellular and molecular analysis.